Introduction
Upper Three Runs Creek is a 20-mile (40-kilometer) waterway that meanders through
hardwood and cypress forests on the 310-square- mile (806-square-kilometer)
Savannah River Site near Aiken, S.C. It empties
into the Savannah River. The creek is a blackwater stream because of its high
concentration of naturally occurring tannic acid that gives the water its tea
color. Scientists have recorded more than 575 species of aquatic insects in
Upper Three Runs, probably giving it the second highest level of aquatic insect
biodiversity in the world. Breitenback Creek in southern Germany contains a
recorded 635 aquatic insect species. The next highest levels of aquatic insect
biodiversity are found in tropical streams in Malaysia and Australia, but both
have fewer than 400 species.
Wildlife
Though scientists have documented more than 575 species of aquatic insects in
Upper Three Runs Creek, the figure does not include other species of invertebrates.
These include round worms, crayfish, other large crustaceans and mussels. Altogether,
the stream may contain as many as 700 invertebrate species.
Upper Three Runs is the only known locality of the blackbanded sunfish and the
turquoise darter in the Savannah River drainage.
Plant life
The bottomland area and adjacent valley slopes surrounding Upper Three Runs
Creek are important habitats for plants. Eight plant species that are listed
on federal and/or state lists of species of special status are found in this
set-aside area. They are: sandhill seedbox, milk pea, bog spice bush, Nestronia,
green- fringed orchid, Oconee azalea, spatulate seedbox and Chapman's sedge.
UTR Research
Scientists at Savannah River Ecology Laboratory believe Upper Three Runs Creek
has such a high level of biodiversity because of a suite of unique characteristics
working in concert. For one, Upper Three Runs is a spring-fed stream, which
results in colder water temperatures. Thus, typically northern and mountain
species of aquatic fauna coexist with the native southeastern species.
Researchers are using molecular biology techniques such as fatty acid analysis,
physiological determinations, reverse genome probing and RNA sequencing, to
learn more about the microbial communities that inhabit Upper Three Runs Creek.
Microbes control most ecosystem level processes, such as nutrient and mineral
cycling, which are necessary for the growth of other organisms. If scientists
can determine that a habitat contains a healthy and diverse community of microbes,
they can say it is a healthy environment. If there are only a few microbes present,
an ecosystem's functions are limited. Waste products are not broken down; they
accumulate in the environment.
Range
Blackwater streams, such as Upper Three Runs Creek, are found throughout the
southeastern United States. Many, however, suffer from pollution and siltation,
which Upper Three Runs has only experienced at a minimum because of its location
within the controlled access area of the U.S. Department of Energy's Savannah River Site. The stream also flows through a DOE- protected
research set-aside area that cannot be developed for industry or forestry.
Did You Know?
Since the SRS was established in 1951, the overall management
policy has called for the stream to be a "control," receiving as little impact
as possible from site operations. No effluents are discharged into the upper region of
Upper Three Runs Creek. Also, all routine forest management has ceased on the floodplain
and adjacent valley slopes.
Upper Three Runs is home to a number of invertebrate species found
nowhere else in the world and many that are rare. One species found only in Upper Three
Runs is a caddisfly called Cheumatopsyche richardsoni. Three other caddisflies of the same
genus also live in the stream. Thus C. richardsoni was an ideal species to study the
effect of its unique native status on genetic diversity in the stream. As expected,
Savannah River Ecology Laboratory researchers found that the genetic diversity of C.
richardsoni was low, which limits its ability to disperse to other locations. Also,
researchers recently identified a new family of isopods from that inhabits an aquatic zone
beneath Upper Three Runs. The isopod family's nearest living relatives are found in
eastern Europe in a similar habitat.
The Upper Three Runs/Tinker Creek Research Set-Aside at SRS has
been the focus of many ecological studies conducted by scientists at the Savannah River
Ecology Laboratory and their colleagues from other institutions. Studies include research
on wood ducks, red-cockaded woodpeckers, small mammals, aquatic insects, fish communities,
rare and threatened plants, forest dynamics, biological and chemical cycling of elements
in streams and seasonal fluctuations of acids in soils.
Studies of Upper Three Runs Creek are giving scientists an example
of a relatively protected stream that can be used as a bench mark for environmental
mitigation and restoration of polluted waterways.
This fact sheet was produced by the Outreach Program
of the Savannah River Ecology Laboratory.
